\subsection{MSVC 6.0}

Just found in some old code:

\begin{lstlisting}[style=customasmx86]
                 fabs
                 fild    [esp+50h+var_34]
                 fabs
                 fxch    st(1) ; first instruction
                 fxch    st(1) ; second instruction
                 faddp   st(1), st
                 fcomp   [esp+50h+var_3C]
                 fnstsw  ax
                 test    ah, 41h
                 jz      short loc_100040B7
\end{lstlisting}

\myindex{x86!\Instructions!FXCH}
The first \INS{FXCH} instruction swaps \TT{ST(0)} and \TT{ST(1)}, the second do the same, so both do nothing.
This is a program uses MFC42.dll, so it could be MSVC 6.0, 5.0 or maybe even MSVC 4.2 from 1990s.

This pair do nothing, so it probably wasn't caught by MSVC compiler tests.
Or maybe I wrong?

